Search Engine Basics

Search Engine and SEO Glossary

Every term used across this site, defined in forty to sixty words so the answer stands on its own. Each entry links to a full explanation and to the guide the term belongs to.

21 terms

A

  • AI Overview

    An AI Overview is a generated summary shown above search results, produced by retrieving pages…

  • Anchor text

    Anchor text is the visible, clickable text of a hyperlink. Search engines use it as…

B

  • Backlink

    A backlink is a hyperlink on one site pointing to a page on another. Search…

  • BM25

    BM25 is a ranking function that scores a document against a query using term frequency…

C

  • Canonical URL

    A canonical URL is the address a search engine treats as the primary version of…

  • Crawl budget

    Crawl budget is the number of URLs a search engine will fetch from a site…

  • Crawl frontier

    The crawl frontier is the queue of URLs a crawler knows about but has not…

  • Crawler

    A crawler is a program that requests URLs over HTTP, stores the responses, extracts the…

F

  • Featured snippet

    A featured snippet is an organic result promoted to the top of the results page…

I

  • Indexing

    Indexing is the stage where a fetched page is rendered, parsed, tokenised and written into…

  • Inverted index

    An inverted index is a data structure that maps each term to the list of…

N

  • noindex

    noindex is a directive, delivered as a meta robots tag or an X-Robots-Tag HTTP header,…

R

  • Redirect

    A redirect is an HTTP response telling a client that a resource is at a…

  • Rendering

    Rendering is the step where a search engine executes a page's JavaScript to see the…

  • robots.txt

    robots.txt is a plain text file at the root of a host that tells crawlers…

S

  • Search intent

    Search intent is what a user is actually trying to accomplish with a query, as…

  • SERP

    SERP stands for search engine results page: the page returned in response to a query.…

  • Soft 404

    A soft 404 is a URL that returns a 200 OK status while its content…

  • Structured data

    Structured data is machine-readable markup, usually JSON-LD using schema.org vocabulary, that describes what a page…

T

  • TF-IDF

    TF-IDF is a scoring formula that weighs a term by how often it appears in…

X

  • XML sitemap

    An XML sitemap is a file listing the URLs on a site that its owner…